| Habitat is the living environment on which living organisms depend.At this stage,the comprehensive river management lacks the attention of aquatic ecological management technology based on the characteristics of natural rivers,which causes the degradation of river habitat and seriously affects the habitat of aquatic organisms and reproduction.The restoration of habitat usually requires the establishment of analysis planning and construction based on protected species,while the traditional habitat restoration techniques mainly use the knowledge and experience of experts to determine the priority protection of species,lacking systematic and complete evaluation methods,but also affected by the accuracy of evaluation methods,practical application results are often difficult to achieve the planed ecological objectives.This study summarizes the research status of priority protection fish assessment,habitat assessment,habitat restoration practice,and analyzes the deficiencies of the current research,and under the guidance of improving the water ecosystem structure and biological health concept,carries out the planning and practical application of river habitat assessment based on priority protection of fish to provide reference for research of habitat restoration of the same type of rivers at home and abroad.Based on the characteristics of non-endangered protected species in the Qingyi river(Xuchang section)watershed,a set of multi-dimensional evaluation methods for priority protected fish is proposed.The evaluation system covers habitat suitability,structural stability,species endangered degree,human disturbance degree,genetic value and species value 6 first-level indicators and 12 second-level indicators,the weight of each indicator was determined by analytic hierarchy process,based on the data of fish resources,combined with scientific evaluation methods,the Ctenopharyngodon idellus,Opsariichthys bidens,Culter alburnus was finally screened out.Then the selection results were discussed,and the rationality of evaluation results of priority protection fish were analyzed.According to the current situation of the main and tributary habitats of the Qingyi River Basin(Xuchang section)and the requirements of river flooding,combined with the technical characteristics and applicable conditions of micro-habitat restoration technologies such as spur dams,gravel groups,deep troughs and shallows,the habitat suitable for flooding rivers was determined.Taking the Baling River,a tributary of the Qingyi River as an example,the layout location and related parameters of micro-habitat restoration measures were determined according to the regional characteristics,and the impact of flood discharge was analezed.In order to improve the simulation accuracy,the fitness index model based on mamdani fuzzy logic,the one-dimensional model HEC-RAS and the two-dimensional habitat model River2D for inferring the water surface line were established in this paper,and the three models were coupled to simulate the effect of microhabitat restoration measures on the river hydrodynamic and spawning habitat area of priority protection fish under different flow rates.The results show that under the flow conditions which the annual average flow rate is 0.88m~3/s and the annual maximum flow rate is 2.0m~3/s,the micro-habitat improvement measures still have a good performance on the meso-scale.It will be helpful to rebuild fish habitat by constructing micro habitat restoration technology,but still need to combine ecological flow and other methods to promote the restoration of river habitat.Under the ecological flow of 4.0-5.0m~3/s,the proportions of the habitat area of the Ctenopharyngodon idellus,Opsariichthys bidens,and the Culter alburnus have reached more than 20%,which can meet the demand of suitable area requirements of spawning grounds.In addition,this study combined with the current situation of water shortage of and multiple dams regulation in the Qingyi River,it is proposed that the periodic pulse flow should be implemented during the spawning period of the fish,and the natural fish resources should be quickly restored by combining the artificial proliferation and release activities.According to the multiple biological surveys of fish before and after application,this paper analyzes the application effects of habitat restoration projects through the three biodiversity analysis methods:Shannon Wiener Index,Margalef Abundance Index,and Pielou Uniformity Index.After that,a total of 11 new species such as bar mackerel,betta and black fish appeared in the study section,and the new fish have similar hydrodynamic preferences and ecological characteristics as the priority protection fish.It has been significantly improved,and the fish diversity in more than half of the river has increased by more than 80%,and the fish has shown obvious spatial heterogeneity with the construction of habitat restoration measures.The application effect is consistent with the habitat simulation effect,which indirectly shows that the assessment and implementation of this study are scientific and reasonable from the screening of priority fish protection to the construction of application recovery technology system. |
